Dog and handler on a pile of rubble near Ground Zero. Photo: Animal Planet

In the aftermath of the attack on the World Trade Center, heroes came in all shapes, sizes and species.

Animal Planet’s “Hero Dogs of 9/11” tells the remarkable tale of how dogs played an important part on America’s darkest day.

“We wanted to just celebrate dogs and we felt that this theme would really transcend typical 9/11 stories,” said executive producer Tanya Kelen.

The hour-long special tells the remarkable stories of three survivors, including Genelle Guzman-McMillan, the last person pulled alive from the rubble. According to eyewitness accounts, Guzman-McMillan was found buried alive by search and rescue dogs.

This emotional special, told through first-person accounts, archival photos, videos and striking recreations, focuses on the 27 hours after the planes struck the Twin Towers and the over 300 dogs that came from across the continent to help.

Insight is given as to what makes a dog a good candidate to be a search and rescue dog and how they are trained. It also shows how discouraged the dogs became when no live finds were made. They did not, however, stop searching and eventually worked alongside cadaver dogs to locate remains.

Rescue workers explain how the dogs were able to search the debris pile and go places that were too unstable for people. The dogs were also able to cover large areas far quicker than their human counterparts.

Therapy dogs were also on hand to give comfort and lift moral for the tireless workers.